In order to enhance the recovery of scrap metal contaminated with combustible hydrocarbons, it is desirable to remove the contaminants prior to melting the scrap metal. It has been recognized that organic contaminants such as paint and lacquer, which are presently coated onto aluminum beverage cans, have heat content which can be recovered to heat incoming material. Currently the use of the heat content of hydrocarbon contaminants has been used in drying and oxidizing methods. Three prior art patents which teach the usefulness of preheating with burned hydrocarbons are U.S. Pat. Nos. 2,795,054: 3,005,699; and 3,623,235. In addition, a method of using vaporized fumes to preheat material in a rotary kiln is taught in U.S. Pat. No. 4,548,651 and in U.S. application Ser. No. 750,337, entitled "Scrap Metal System", which was filed June 28, 1985 and allowed Feb. 26, 1986. This patent application is assigned to Aluminum Company of America. While many of the above-described methods work as intended, there is still a need for a process and an apparatus which are highly efficient, relatively pollution-free, easily operated, and capable of handling large quantities of scrap metal.
Now such a process and apparatus have been invented which can more efficiently handle large quantities of scrap aluminum cans containing a lacquer or paint coating thereon.